1. Field of the Invention
The present invention relates to a method for manufacturing a fluorescent lamp. More specifically, the present invention relates to a method for manufacturing a fluorescent lamp in which a lead wire is not provided with a fixing bead (glass bead) and a method for manufacturing a fluorescent lamp by which a continuous process from the holding of a lead wire to the exhaustion of a glass tube can be conducted using a specific jig.
2. Related Background Art
Conventionally, as means for reducing a material cost and for making effective use of a luminescent length by omitting a stem for assembling an electrode, a method for manufacturing a stemless fluorescent lamp is known. For example, JP 6(1994)-290735 A describes a manufacturing method in which an electrode is attached to a pair of lead wires while the pair of lead wires is fixed with a glass bead, and the pair of lead wires is pinch-sealed to an end portion of a glass tube. Also, a method in which after a pair of thin electrode wires is fixed with a magnet and ends of the pair of electrode wires are fixed with a fixing bead, then one side of the pair of electrode wires is pinch-sealed to a discharge tube and processes such as exhaustion, filling and sealing-off are conducted using an end portion of a glass tube on the side that is not pinch-sealed is known as described in JP 54(1979)-1111 B.
In the above-described discharge lamps, the former one is manufactured as follows: firstly, the pair of lead wires is supported by certain means to be fixed with the glass bead, and then an electrode is attached thereto to form an assembled member. Next, each of the assembled member, an exhaust tube and the glass tube is grasped by their respective grasp means so as to conduct pinch-sealing of the lead wires to the glass tube. Next, the thus prepared glass tubes are collected, carried and transferred for an exhaustion step, and then are subjected to the exhaustion and the following processes to complete the discharge lamp. The latter discharge lamp is manufactured as follows: that is, the pair of long electrode wires is passed through fixing beads at a plurality of portions to form an assembled member, where the pair of long electrode wires is held by a member partially constituted with a magnet formed at one side surface. After this assembled member is supported by another means and is inserted in the narrow glass tube whose both ends are open, one side of the open ends is pinch-sealed. Next, the thus prepared glass tube is transferred to another step, where a process such as exhaustion is conducted using the other open end.
However, the above-described conventional methods for manufacturing a fluorescent lamp have the following problems: that is, as for the former method, since the step for fixing the lead wires with the glass bead is conducted prior to the attachment of the electrode to the lead wires, the pinch-sealing process of the glass tube requires separate grasp of the assembled member and the exhaust tube with respect to the lead wires. Therefore, there is considerable loss of man-hours and material, and the manufacturing process becomes complicated. In addition, the effective luminescent length becomes shortened by a rise in the electrode position due to the presence of the glass bead.
As for the latter method, the electrode member before the attachment of the fixing bead is held with the magnet formed partially and only at one side. Therefore, a holding power is weak, so that the electrode member might be detached before the insertion into the fixing bead, which would increase inefficiency of the process. Also, supporting means is required for pinch-sealing the assembled member of the electrode member to the glass tube, which would make the process complicated. Further, in order to conduct a process such as exhaustion using the open end of the glass tube on the side that is not pinch-sealed, an exhaust tube with a small diameter separately has to be connected, and therefore loss in material and inefficiency of the process would be generated.